Three types too many


You might have read this week that there is now a “Type 3” diabetes—Alzheimer's disease. Scientists at Northwestern University believe that Alzheimer's disease is caused by insulin resistance in the brain. They even use the term Type 3 diabetes in the abstract of their study.

The differences between Type 1 and Type 2 diabetes are apparently not confusing enough. Now we need to add a Type 3 diabetes into the mix?

The geniuses at the American Diabetes Association came up with the Type 1 and Type 2 naming conventions in 2000 to move away from basing the names on treatment or age at onset. (Interestingly, the Juvenile Diabetes Research Foundation continues to use the word “juvenile” in its name.)

How can we better differentiate the diseases? Instead of Type 1, we could say “autoimmune diabetes” or “autoimmune insulin deficiency” or “genetic diabetes”? Instead of Type 2 we could say “insulin-resistance” or “insulin-deficient diabetes”? Would a rename make it less confusing for John Q. Public or make no difference? Personally, I don’t think both diseases can share the name “diabetes” or the two will forever be confused.

We’ve talked about the name confusion at length on Tudiabetes and there have also been recent articles discussing the subject in The New York Times and other publications. Why is the ADA so reluctant to make a name change? I think it is necessary with the explosive growth of Type 2 diabetes worldwide.


There are already at least 8 types of diabetes identified if you count the 6 different forms of mongenetic diabetes which are different from either autoimmune or insulin resistant diabetes. I have one of them, and it is frustrating how ignorant even endos can be about the existance of these different forms.

Beyond that “Type 2” is a garbage can diagnosis into which are put everyone who isn’t autoimmune. As we understand more about genes we are finding that there are many dozens of genes causing “type 2” and that they affect different parts of the glucose metabolism cycle.

Some “type 2s” aren’t insulin resistant, most are.

“Diabetes” really is a symptom, high blood sugar, not one disease.


There was some discussion at the ADA Scientific Sessions about whether it was time to revisit the current classification system, but I will not hold my breath waiting for that to happen.

The last time they revisited this issue was in 2003, and they adopted the current type numbers to move away from a naming convention that “to move away from a system that appears to base the classification of the disease, in large part, on the type of pharmacological treatment used in its management toward a system based on disease etiology where possible”. Unfortunately, those recommendations made it even more confusing rather than less confusing.

Does the name “type 1” or “type 2” classify the disease based on etiology? No way. The ADA should have clarified the issue by formally renaming insulin-dependent diabetes as “immune-mediated diabetes” and type 2 diabetes as “insulin-resistance mediated diabetes,” (as well as several other “types” but has instead created even more confusion by giving them confusing type numbers instead of Notice that other similar conditions do not have this problem. For example, although Ulcerative Colitis and Crohn’s Disease are both inflamatory bowel diseases, few people ever confuse them as they routinely do with type 1 and type 2 diabetes because their names are very clear and distinct from one another.

To reference the 2003 ADA classifications, see